Method of constructing lamp-shades.



Patented Aug. 14, I900.

0. A. MYGATT. METHOD OF CONSTBUGTING LA MP SHADES.

pplication filed. Inn.

WITNESSES one A. MYGATT, on NEW YORK, N. Y.

METHOD OF CONSTRUCTING LAMP-SHADES.

SPECIFICATION forming part of Letters Patent No. 655,728, dated August 14, 1900. Application filed January 19, 1899. Serial No. 702,687. (No specimens.)

To aZZ whom it may concern.-

Be it known that I, OTIS A. MYGATT, a citi zen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and The object of the invention is to produce a single-piece globe having external ribs or prisms, with the surfaces of such ribs or prisms at determined angles.

Heretofore glass lamp-shades have been made with the outer surfaces ribbed horizontally, as described in Patent No. 593,348, of November 9, 1897, to Blondel and Psaroudaki. It must be understood that these horizontal ribs on the outer surface of the shade or globe described in such patent have their faces or angles arranged with definite relation to the position such faces occupy on the globe with relation to the position of the light within the globe or shade. Thus it is necessary that the faces and angles of the ribs bear a different relation to the globe when the rays of light are to be thrown downward than when the rays of light are thrown horizontally, and for each kind of globe or shade the ribs must be constructed on a carefully-calculated predetermined plan in which the laws of reflection and refraction of light are considered, and the ultimate position of such faces and angles must be as thus calculated in order to give the desired result; but in molding globes or other forms of shades in which the end diameter is less than the diameter between the ends if it is desirable to have the faces of the ribs of the upper and lower hemispheres at angles acute to the surface in opposite directions or, in fact, if the ribs are at all undercut it becomes impossible under some conditions to open a mold of two-part construction, and a more complex mold is objectionable. Consequently such globes have heretofore been made in separate halves joined at the vertical center and usually held together by wires fastening the parts by passing vertically through the ribbed shades or by metallic bands joining the parts or halves. I have inventeda method of making such globes in a single piece, with the faces of the ribs projected in the desired direct-ion, as I will now explain.

Figure 1 indicates a transverse section of a mold and plunger with the inclosed article as first formed. Fig. 2 indicates the article in the holder undergoing the formative action of the second step'in the process, a section being shown. Fig. 3 is a section. of the glass article or globe with external ribs after bending.

The form of the external ribs is first carefully calculated with reference to the position its plane surfaces are to occupy on the completed globe or spheroid.

The moldAis made as to the closed endor approximately one-half of the sphere in such manner as to form the ribs to the desired angle of the completed article-say from a to b, Fig. 1. The mold from Z; to 0, however, is made either cylindrical or flaring, the latter form being shown. The faces of the ribs in this part of the mold are made not to the ultimate angle, but to such angles as when the cylinder is drawn in to spheroidal or other ultimate form they will assume the desired angle. To construct a mold, therefore, requires careful calculation and construction, due regard being paid tothe compression of the glass or to the flowing of the glass while plastic. After the article K is removed from the mold A B C it is clasped by a holder D, which embraces only the completed hemisphere or enough thereof to hold the article.- The cylindrical or open part of the article is then placed in the glory-hole of a glass-furnace and the part not in the holder is heated to a plastic condition. While soft it is rolled back and forth on a table or turned in the hand, and a bearing piece or tool E, prefer-' ably of wood, is pressed on the side of the open end of the article. The open end of the article is thus pressed or spun in until a spheroidalordrawn-informisattained. The pressure of the bearer or tool E gradually brings the cylinder to spheroidal or tapering form. The ribs H have their angles changed, as indicated at H, the glass of the body being compressed and the angle of the ribs being changed with relation to said body by the general outline, and if the mold is properly calculated the plane faces of the ribs may be brought to almost any desired angle.

In referring to globes it will be understood that the invention applies to all ribbed lampshades in which the ultimate angles of the faces of the ribs difier from the angles pressed on the plastic glass in the mold.

From the foregoing it will be understood that the prisms cut in or on that part of the mold which forms that part of the glass which is afterward reheated and altered in shape are-not in their proper position as related to the center of light in the globe, and a shade formed in the mold, with the subsequent intention of re-forming by this process, would not have its ribs in the position to give definite direction to light-rays contemplated by the patent referred to.

subsequent treating that the faces and angles It is only after the v of the ribs have their proper predetermined relation to the shade or globe.

That I claim is 1. The method of producinga ribbed hollow article of glass, which consists in molding the article With open end and with projecting external ribs having a predetermined relation to the ultimate angles, heating the open end of the article and shaping down the open end, until the ribs assume the desired pre determined position or angular relation relatively to the body of the article, substantially as described.

2. The method of producing a ribbed lampshade which consists in molding the shade with external circumferential ribs projecting at angles and in planes other than the angles and planes of the completed shade but having definite relation thereto, heating a part of the molded shade, and shaping in the heated portion to give to the ribs the predetermined angle and to the shade the desired form, substantially as described.

In testimony whereof I affix my signature in presence of two witnesses.

OTIS A. MYGATT.

Witnesses:

W. A. BARTLETT, M. E. BROWN. 

